libitm/alloc.cc

   1 /* Copyright (C) 2009-2024 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson <rth@redhat.com>.
   3
   4    This file is part of the GNU Transactional Memory Library (libitm).
   5
   6    Libitm is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    Libitm is distributed in the hope that it will be useful, but WITHOUT ANY
  12    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14    more details.
  15
  16    Under Section 7 of GPL version 3, you are granted additional
  17    permissions described in the GCC Runtime Library Exception, version
  18    3.1, as published by the Free Software Foundation.
  19
  20    You should have received a copy of the GNU General Public License and
  21    a copy of the GCC Runtime Library Exception along with this program;
  22    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23    <http://www.gnu.org/licenses/>.  */
  24
  25 #include "libitm_i.h"
  26
  27 namespace GTM HIDDEN {
  28
  29 void
  30 gtm_thread::record_allocation (void *ptr, void (*free_fn)(void *))
  31 {
  32   // We do not deallocate before outermost commit, so we should never have
  33   // an existing log entry for a new allocation.
  34   gtm_alloc_action *a = this->alloc_actions.insert((uintptr_t) ptr);
  35
  36   a->free_fn = free_fn;
  37   a->free_fn_sz = 0;
  38   a->allocated = true;
  39 }
  40
  41 void
  42 gtm_thread::forget_allocation (void *ptr, void (*free_fn)(void *))
  43 {
  44   // We do not deallocate before outermost commit, so we should never have
  45   // an existing log entry for a deallocation at the same address.  We may
  46   // have an existing entry for a matching allocation, but this is handled
  47   // correctly because both are complementary in that only one of these will
  48   // cause an action at commit or abort.
  49   gtm_alloc_action *a = this->alloc_actions.insert((uintptr_t) ptr);
  50   a->free_fn = free_fn;
  51   a->free_fn_sz = 0;
  52   a->allocated = false;
  53 }
  54
  55 void
  56 gtm_thread::forget_allocation (void *ptr, size_t sz,
  57                                void (*free_fn_sz)(void *, size_t))
  58 {
  59   // Same as forget_allocation but with a size.
  60   gtm_alloc_action *a = this->alloc_actions.insert((uintptr_t) ptr);
  61   a->free_fn = 0;
  62   a->free_fn_sz = free_fn_sz;
  63   a->sz = sz;
  64   a->allocated = false;
  65 }
  66
  67 namespace {
  68 struct commit_cb_data {
  69   aa_tree<uintptr_t, gtm_alloc_action>* parent;
  70   bool revert_p;
  71 };
  72 }
  73
  74 static void
  75 commit_allocations_2 (uintptr_t key, gtm_alloc_action *a, void *data)
  76 {
  77   void *ptr = (void *)key;
  78   commit_cb_data *cb_data = static_cast<commit_cb_data *>(data);
  79
  80   if (cb_data->revert_p)
  81     {
  82       // Roll back nested allocations, discard deallocations.
  83       if (a->allocated)
  84         {
  85           if (a->free_fn_sz != 0)
  86             a->free_fn_sz (ptr, a->sz);
  87           else
  88             a->free_fn (ptr);
  89         }
  90     }
  91   else
  92     {
  93       // Add allocations and deallocations to parent.
  94       // ??? We could eliminate a (parent) allocation that matches this
  95       // a deallocation, if we had support for removing all accesses
  96       // to this allocation from the transaction's undo and redo logs
  97       // (otherwise, the parent transaction's undo or redo might write to
  98       // data that is already shared again because of calling free()).
  99       // We don't have this support currently, and the benefit of this
 100       // optimization is unknown, so just add it to the parent.
 101       gtm_alloc_action* a_parent = cb_data->parent->insert(key);
 102       *a_parent = *a;
 103     }
 104 }
 105
 106 static void
 107 commit_allocations_1 (uintptr_t key, gtm_alloc_action *a, void *cb_data)
 108 {
 109   void *ptr = (void *)key;
 110   bool revert_p = (bool) (uintptr_t) cb_data;
 111
 112   if (revert_p == a->allocated)
 113     {
 114       if (a->free_fn_sz != 0)
 115         a->free_fn_sz (ptr, a->sz);
 116       else
 117         a->free_fn (ptr);
 118     }
 119 }
 120
 121 /* Permanently commit allocated memory during transaction.
 122
 123    REVERT_P is true if instead of committing the allocations, we want
 124    to roll them back (and vice versa).  */
 125 void
 126 gtm_thread::commit_allocations (bool revert_p,
 127     aa_tree<uintptr_t, gtm_alloc_action>* parent)
 128 {
 129   if (parent)
 130     {
 131       commit_cb_data cb_data;
 132       cb_data.parent = parent;
 133       cb_data.revert_p = revert_p;
 134       this->alloc_actions.traverse (commit_allocations_2, &cb_data);
 135     }
 136   else
 137     this->alloc_actions.traverse (commit_allocations_1,
 138                                   (void *)(uintptr_t)revert_p);
 139   this->alloc_actions.clear ();
 140 }
 141
 142 } // namespace GTM